KR101053358B1 - Communication node, communication system ring configuration method, and ring establishing method - Google Patents

Abstract

An object of the present invention is to obtain a communication node used in a ring-shaped communication system in which Ethernet nodes are connected to each other without using a repeater. As a communication node 10 constituting a communication system in which a plurality of communication nodes 10 connected in a one-to-one manner are connected in a ring shape by Ethernet doubled into a regular ring 1 and a standby ring 2. , A port 11, B port 14, and the frame output from the B port 14 at the time of normal communication, the reception process is performed, and the normal ring (1) from the B port 14 Frame is transmitted, and when another communication node performs a loopback process due to a communication error, only the transmission process is performed without receiving the frame from the standby system ring 2 of the B port 14. The communication processing part 17 which transmits a frame from the port 11 to the atmospheric ring 2 is provided.

Description

Ring configuration method and ring establishment method of communication node and communication system {COMMUNICATION NODE, COMMUNICATION SYSTEM RING CONFIGURATION METHOD, AND RING ESTABLISHING METHOD}

The present invention relates to a communication node used in an Ethernet-based ring-shaped communication system that performs communication by connecting Ethernet (registered trademark) in a ring shape, and token-ring communication without a master in the communication system. The present invention relates to a ring configuration method and a ring establishment method of a communication system.

Background Art Conventionally, a form of connecting a communication terminal (hereinafter referred to as a communication node) with a fiber-distributed data interface (FDDI) to establish a network is known (see Non-Patent Document 1, for example). In this FDDI, a network is generally constructed to connect communication nodes in a ring shape. In a network using FDDI, abnormalities such as the disconnection of a cable constituting the first loop and a failure of a communication node, etc. occur in the first loop where data is transmitted in a normal state. A double loop structure is taken, consisting of a second loop for loop backing to separate and to enable communication in the normal part.

In FDDI, a token passing system that uses transmission right data called tokens to control the collision of data transmitted between communication nodes connected to a network does not occur. In this token passing method, a token flows on the first loop, and a communication node that wants to transmit data captures and inserts this token, instead, sheds data that it wants to transmit, and releases the token again to the network when the transmission ends. By releasing, always letting one terminal use a cable at a time.

[Non-Patent Document 1] Karl F. Pieper, William J. Cronin Jr., Wendy H. Michael, Supervisor of Naoki Mizutame, `` Building FDDI Technical Details-100Mbps LAN, '' First Edition, Public Publishing, August 1993 30 days, p.67-73

However, at present, a form of establishing a network by connecting communication nodes between Ethernets is widespread. This Ethernet uses CSMA / CD (Carrier-Sense-Multiple-Access / Collision-Detection), which secures communication rights while avoiding collisions and transmits data to all connected communication nodes when a communication node connected to the Ethernet transmits data. ) Method is adopted. In order to function this method, the connection form of a communication node in Ethernet is centered on one cable which becomes a trunk line, a branch cable is extended at a suitable distance therefrom, and a plurality of communication nodes are connected. Two topologies configured by arranging a bus topology and a star topology constituted by arranging a plurality of communication nodes in a radial manner centering on one control device (hub). There is.

However, in Ethernet, since the terminal device connected to the network terminates (discards) the Ethernet frame, the above-described bus topology and star topology exist, but there is a problem that a ring topology does not exist. In addition, in a star topology, if a failure occurs in a repeater (hub), all the communication nodes connected to the repeater become incapable of communication, or the communication specialist concentrates on the repeater, and the repeater becomes a bottleneck of communication performance. . In addition, in the conventional Ethernet topology, there is a problem in that collision or congestion occurs, and it is difficult to guarantee timeliness.

In addition, when the network is established, it is necessary to pass station information to communication nodes other than the self communication node existing on the network so that each communication node can recognize the configuration of the network. At this time, when the source of the station information receives a response from another communication node, it is necessary to confirm whether the station information has been distributed to all communication nodes on the network, but there is a problem that the processing is complicated.

In addition, although the above-described FDDI exists as a ring topology, there is a problem that a network using FDDI is not as popular as a network using Ethernet. In addition, even when a network using Ethernet is configured in a ring topology, there is a problem that the standard of FDDI cannot be directly applied to Ethernet.

The present invention has been made in view of the above, and an object thereof is to obtain a communication node used in an Ethernet-based ring-shaped communication system in which Ethernet nodes are connected to each other without using a repeater. It is also an object of the present invention to obtain a communication node capable of easily constituting a ring excluding a failure and a ring configuration method of a communication system when a failure is found in a network of a ring topology constructed of Ethernet.

In addition, in an Ethernet-based ring-shaped communication system, an object of the present invention is to obtain a path establishment method in a ring-shaped communication system that defines a sequence required for communication between communication nodes. Specifically, in an Ethernet-based ring-shaped communication system, it is also an object to obtain a communication node capable of confirming that a path formed by a normal communication node is configured in a ring shape, and a ring establishment method of the communication system.

In addition, in an Ethernet-based ring-shaped communication system, it is another object to obtain a communication node capable of easily confirming whether or not station information has been distributed to all communication nodes on a network after the ring is established, and a ring establishment method of the communication system. It is done.

In order to achieve the above object, a communication node according to the present invention includes a normal-system ring for transmitting a frame when the communication state is normal, and an atmospheric ring used for transmission of the frame when the communication state is abnormal. A communication node constituting a communication system in which a plurality of communication nodes connected in a one-to-one manner by Ethernet duplexed by a standby (system ring) are connected in a ring shape, the input node of the regular ring and the standby ring of the standby ring. A first port having an output, a second port having an output of the normal ring and an input of the atmospheric ring, and a frame input from an input of the normal ring of the first port during normal communication For the case where the receiver performs the reception process, transmits the frame from the output section of the regular ring of the second port, and another communication node performs the loopback process due to a communication error, The frame input from the input section of the standby system ring of the second port is not received, and only the transmission process is performed. The frame is transmitted from the output section of the standby system ring of the first port, and the adjacent communication node is transmitted. And a communication processing means for performing loop back processing by connecting a normal ring and a standby ring of ports connected to the adjacent communication node with a port connected to the adjacent communication node when a communication error occurs. When the power is turned on or when the self-communication node performs a loopback process to form a new ring, a ring establishment confirmation frame embedded with an issuance time is generated, and the ring establishment confirmation frame that has traversed the ring is generated. Ring establishment confirmation frame issuing means for stopping the issuing of subsequent ring establishment confirmation frames upon reception; Frame traversal time calculation means for calculating a frame traversal time issued by the ring establishment confirmation frame issuing means and subtracting the issuance time in the ring establishment confirmation frame from the time when the ring establishment confirmation frame that has traveled the ring is received. and; And ring establishment determination means for determining whether or not a ring establishment confirmation frame flowing in the ring is not detected during the frame circulation time or more after the issuance of the ring establishment confirmation frame.

According to the present invention, by connecting the communication nodes in a ring shape, it is not necessary to use the repeaters necessary for the connection form of the star topology or the bus topology, thereby eliminating the incommunication state of all communication furnaces caused by the failure of the repeaters. Can avoid the situation where the communication specialist concentrates on the repeater. In addition, since the repeater can be reduced, the cost of the system construction can be reduced.

EMBODIMENT OF THE INVENTION Below, with reference to an accompanying drawing, preferable embodiment of the ring constitution method and ring establishment method of this invention and a communication system is described in detail. In addition, this invention is not limited by these embodiment. Below, the outline of the structure of this invention common to each embodiment is demonstrated, and each embodiment is demonstrated after that.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows schematic structure of the ring-shaped communication system of Ethernet base which concerns on this invention. This ring-shaped communication system has a configuration in which a plurality of communication nodes (denoted as nodes; 10-1 to 10-4) connected in a one-to-one manner by Ethernet are connected in a ring shape. Here, the Ethernet cable connecting between the communication nodes 10-1 to 10-4 is a regular ring 1 for carrying the frame in a right turn in the ring-shaped communication system shown in the solid line and indicated by a dotted line. It is likewise duplicated by two rings, which are atmospheric ring 2 carrying the frame in a left turn. The regular ring 1 is a ring used when the cables and the communication nodes 10-1 to 10-4 constituting the ring-shaped communication system are in a normal state. In addition, when an abnormality occurs in any one of the communication nodes 10-1 to 10-4 and the cable constituting the ring-shaped communication system, the standby system ring 2 loops back the above-mentioned point as described later. Is a ring used to separate from the system.

FIG. 2 is a block diagram schematically showing a configuration of a communication node constituting the ring-shaped communication system of FIG. 1. The communication node 10 includes two ports 11 and 14 for connecting an Ethernet cable between adjacent communication nodes and processing of frames received from the ports 11 and 14 or between other communication nodes. The communication processing part 17 which performs the process for establishing a path | route is provided.

The port consists of two ports: A port (labeled Port A in the drawing; 11) and B port (labeled Port B in the drawing; 14). A port 11 has a regular input 12 for receiving a frame from the regular ring 1 and a standby output 13 for transmitting a frame to the standby ring 2. In addition, the B port 14 includes a normal system output unit 16 for transmitting a frame to the normal system ring 1 and a standby system input unit 15 for receiving a frame from the atmospheric system ring 2. In addition, A port 11 corresponds to the 1st port of a claim, and B port 14 corresponds to the 2nd port similarly.

The communication processing unit 17 reads the frame from the regular ring 1 received at the normal channel input unit of the A port 11 once, and if necessary, performs a predetermined process and then normalizes the B port 14. A frame output from the A port 11 is transmitted as it is from the system output section to the regular ring 1 while the frame from the standby system ring 2 received at the standby system input section of the B port 14 is not read. Send to the department. More specifically, only a frame outputted from the B port 14 in normal operation is subjected to a predetermined process, if necessary, to a frame flowing from the B port 14 to the A port 11 in the communication node. No processing is done for this.

In such an Ethernet-based ring-shaped communication system, communication in a normal state is performed using a token frame for each communication node 10-1 to 10-4 to acquire a communication right in the regular ring 1. . The communication node 10 which wants to perform communication acquires a communication right by receiving the token frame which flows in the regular system ring 1 in the formal system input part 12 of the A port 11. The communication node 10 which has acquired the communication right transmits the data frame to be transmitted from the regular system output part 16 of the B port 14 to the regular system ring 1 instead of the token frame. When the transmission of the data frame is completed, the token frame is returned to the regular ring 1 from the regular output unit 16 of the B port 14, and the communication frame 10 is returned to a state where other communication nodes 10 can communicate. .

The above is the outline | summary of the ring-shaped communication system of the Ethernet base common to each embodiment demonstrated below. Hereinafter, each embodiment is described based on this content. In the following description, the communication nodes 10-1, 10-2, 10-3, and 10-4 are referred to as stations 1, 2, 3, and 4, respectively.

In this specification, for the sake of simplicity, the case where the ring-shaped communication system is constituted by four communication nodes 10-1 to 10-4 will be described as an example, but a plurality of communication nodes 10 are ringed by Ethernet. If it is a structure connected in a shape, the following embodiments can be applied.

Embodiment 1.

In the first embodiment, loopback processing in a case where a failure or incorrect connection of a cable occurs in a part of the Ethernet-based ring-shaped communication system shown in FIG. 1 will be described.

<When a failure occurs>

3 is a diagram schematically showing a state in which a failure occurs in a ring-shaped communication system. As shown in Fig. 1, when normal communication using the regular ring 1 is performed in a network in which communication nodes 10-1 to 10-4 of stations 1 to 4 are connected in a ring shape, Fig. 3 As shown in Fig. 2, cable disconnection has occurred between three stations (10-3) and four stations (10-4). In this case, the communication processing unit 17-4 of the four stations 10-4 does not receive signals from the three stations 10-3 at the A port 11-4 of the four stations 10-4. Is continued for more than a predetermined time, and it is determined that a failure has occurred in the cable between the three stations 10-3, and a loopback connecting the standby system input unit and the regular system output unit of the B port 14-4 is performed. Do it. Here, each of the communication nodes (stations) 10-1 to 10-4 constituting the ring-shaped communication system has the same reference value for determining that a failure has occurred due to the time of not receiving a frame. The first detection of an abnormality after the cable disconnection between the 4) and 4 stations (10-4) occurs is the 4 stations (10-4) closest to the failure point of the regular ring (1). As a result, the four stations 10-4 perform the loop back process. Then, an abnormality notification signal indicating that a cable disconnection has occurred between the three stations 10-3 and the four stations 10-4 is transmitted. When the communication processing unit 17-3 of the three stations 10-3 receives the abnormality notification signal, it knows that a cable disconnection has occurred between the three stations 10-3 and the four stations 10-4. In order not to output a frame to the (14-3) side, the loop back which connects the regular system input part of A port 11-3 and a standby system output part is performed.

As a result of the above processing, the three stations 10-3 and four stations 10-4 loop back the transmission path and use the standby system ring 2 to make the three stations 10-3 and four stations at the point of failure. The new ring after disconnecting the cables between (10-4) is reconfigured, and communication of each station is resumed. In the subsequent processing, the communication processing unit 17-3 of the station 3 10-3 reads the frame from the normal ring 1 received at the normal input unit of the A port 11-3 once. After performing a predetermined process, it outputs from the standby system output part of the same A port 11-3 to the standby system ring 2, and the communication processing part 17-4 of four stations 10-4 is a B port. A process of reading a frame from the standby system ring 2 received at the standby system input unit (14-4) once, performing a predetermined process, and then transmitting the same to the regular system output unit of the same B port 14-4. do.

In addition, although FIG. 3 illustrates the loopback by taking the cable disconnection between the three stations 10-3 and the four stations 10-4 as an example, cable disconnection occurs at another location, or a communication node (station; 10-1). Even if 10-4) fails, the ring is reconstructed in the order of the East.

<Ethernet cable is incorrectly connected>

4 is a diagram schematically showing a state in which a cable is incorrectly connected at the time of ring configuration of a ring-shaped communication system. First, as shown in FIG. 4, the connection between the port and the cable in the station 3-10 is incorrect during the operation of connecting the communication nodes 10-1 to 10-4 by cables. That is, the B port 14-2 of the two stations 10-2 and the B port 14-3 of the three stations 10-3 are connected, and the A port 11- of the four stations 10-4 is connected. It is assumed that 4) and A port 11-3 of station 3 10-3 are connected by a cable.

After completion of the cable connection, the communication processing units 17-1 to 17-4 of each communication node 10-1 to 10-4 check whether the connection port of the communication node adjacent to that of the own communication node is normally connected. Specifically, port B 14 of the communication node adjacent to the A port 11 of the self communication node is connected, and port A 14 of the communication node adjacent to the B port 14 of the self communication node is connected. It is confirmed by the negotiation that is performed according to a predetermined rule. At this time, the communication processing unit 17-2 of the station 10-2 assumes that the B port 14-2 of the local station is connected to the B port 14-3 of the station 3 10-3. It is known by the notification and recognizes that the connection port with the three stations 10-3 is wrong. In the Orient, the communication processing unit 17-4 of the four stations 10-4 also shows that the A port 11-4 of the local station is connected to the A port 11-3 of the three stations 10-3. By negotiating, it recognizes that the connection port with the three stations 10-3 is wrong.

The communication processing unit 17 of the communication node that recognizes a misconnection of a connection port performs loopback processing of a port that is not a misconnected port. That is, the communication processing unit 17-2 of the two stations 10-2 loops back at the A port 11-2, and the communication processing unit 17-4 of the four stations 10-4 uses the B port ( Loop back in 14-4).

The ring which isolate | separated the three stations 10-3 which cause a misconnection by the above is comprised. After that, normal communication is performed by this ring.

According to the first embodiment, even when the communication node 10 or the cable constituting the ring-shaped communication system fails, a loopback can be removed to remove the failure point, so that a highly reliable ring shape having fault resistance is provided. It has the effect that a communication system can be realized. In addition, by connecting the communication nodes 10 in a ring shape, it is not necessary to use a repeater necessary for the connection form of a star topology or a bus topology, and thus communication of all communication nodes 10 due to the occurrence of a disturbance of the repeater is impossible. The status can be eliminated, avoiding the concentration of telecom specialists on the repeater. In addition, since the repeater can be reduced, the cost of the system construction can be reduced. In addition, there is an effect that the system construction can be facilitated because a mistaken connection can be found at the time of network construction and the part with the wrong connection can be removed.

Embodiment 2.

In the second embodiment, a method of checking the connection state of a ring performed after a state in which ports between respective communication nodes are correctly connected with an Ethernet cable will be described. For example, as shown in Fig. 1, after one station 10-1 to four station 10-4 are normally connected, the power of each communication node is turned on to perform the ring configuration. At this time, all the communication nodes 10-1 to 10-4 may be in the ON state at the same time, but this may not be the case. For example, even if the three stations 10-3 are turned on due to a failure of the power system, they may not start. In such a case, loop back should be performed at the A port 11-2 of the station 10-2 and the B port 14-4 of the station 10-4. In this way, it is confirmed whether or not the ring-shaped path is configured by the communication nodes 10-1 to 10-4 in the ring-shaped communication system immediately after the power of each communication node 10-1 to 10-4. The procedure of ring establishment confirmation processing to be described will be described below.

5 is a block diagram schematically showing a functional configuration of a communication node according to the second embodiment. The communication processing unit 17 of the communication node 10 of the second embodiment includes a ring establishment confirmation frame issuing unit 21, a frame traversal time calculating unit 22, a frame traversal time storage unit 23, and a ring establishment determination unit ( 24). In addition, the same code | symbol is attached | subjected to the same component as the above-mentioned description, and the description is abbreviate | omitted.

The ring establishment acknowledgment frame issuing unit 21 issues a ring establishment acknowledgment frame for confirming whether or not a ring-shaped path (hereinafter simply referred to as a ring) is established in the ring-shaped communication system after power-on at every predetermined time. . In the ring establishment confirmation frame, the time at which the ring establishment confirmation frame is issued is embedded. When the ring establishment acknowledgment frame 21 receives the ring establishment acknowledgment frame transmitted by the ring establishment acknowledgment frame 21, the ring establishment acknowledgment frame stops issuing the subsequent ring establishment acknowledgment frame and discards the received ring establishment acknowledgment frame.

The frame traversal time calculation section 22, when the ring establishment acknowledgment frame issued by the self-communication node returns from the A port 11, receives the time when the ring establishment acknowledgment frame is received, and the issuing time embedded in the ring establishment acknowledgment frame. Is calculated, the frame establishment time, which is the time when the ring establishment confirmation frame has traveled the ring, is obtained, and stored in the frame circulation time storage unit 23.

The ring establishment determination unit 24 lastly receives the ring establishment confirmation frame issued by the self-communication node or another communication node, and then, after the time more than the frame traversal time, whether the ring establishment confirmation frame has not been detected on the network, is continued. If the state continues for more than the frame traversal time, it is determined that all communication nodes 10 have recognized the connection of the ring.

6A to 6F are diagrams schematically showing an example of a ring establishment confirmation processing procedure in the ring-shaped communication system. First, the ring establishment acknowledgment frame issuing unit 21 of the communication processing unit 17-1 of the station 10-1 receives the ring establishment acknowledgment frame in which the issuing time is purchased from the B port 14-1. ), (FIG. 6A). Here, the station 10-1 transmits the first ring establishment confirmation frame 201-1 at time T1, and the second ring establishment confirmation frame 201-2 at time T2 after a predetermined time has elapsed from time T1. Is sent to the regular ring 1.

Thereafter, since station 1 has not received the ring establishment confirmation frame sent by itself, station 1 10-1 attaches the third and fourth ring establishment confirmation frames 201-3 and 201-4 to the times T3 and T4, respectively. In addition, it transmits to the regular ring 1. After that, the first ring establishment confirmation frame 201-1 first issued by the station 10-1 is lost between the station 10-4 and the station 10-1 for some reason. Let it be (FIG. 6B). In addition, communication nodes 10-2 to 10-4 other than the station 10-1 pass the ring establishment confirmation frames 201-1 to 201-4 from the station 10-1 as they are. Further, since station 1 10-1 has not received the ring establishment confirmation frame sent by itself due to the loss of the first ring establishment confirmation frame 201-1, the fifth station establishes a confirmation frame at time T5. (201-5) is sent to the regular ring.

Subsequently, the station 10-1 receives the second ring establishment confirmation frame 201-2 issued by the port 10-1 from the port A-1, and stores the reception time T6. The frame traversal time calculation unit 22 of the communication processing unit 17-1 of the station 10-1 issuing time T2 embedded in the frame from the reception time T6 of the second ring establishment confirmation frame 201-2. The frame traversal time T (= T6-T2) obtained by subtracting is calculated (Fig. 6C). The calculated frame circulation time is stored in the frame circulation time storage section 23. The ring establishment confirmation frame issuing unit 21 of the communication processing unit 17-1 of the station 10-1 discards the returned second ring establishment confirmation frame 201-2 from the network. In addition, since the ring establishment confirmation frame issuing unit 21 of the communication processing unit 17-1 of the station 10-1 first received the ring establishment confirmation frame issued by itself, the ring establishment confirmation frame issuance is issued after that. Stop (FIG. 6D). Further, up to this point, the station 10-1 has issued the fifth ring establishment confirmation frame 201-5.

Thereafter, the station 10-1 performs a process of receiving and discarding the ring establishment confirmation frame issued by the own station in order, receiving the fifth ring establishment confirmation frame 201-5 issued last, and discarding it. By doing so, the ring establishment confirmation frames 201-1 to 201-5 issued by the station 10-1 from the network (ring) disappear (FIG. 6E). 6A to 6E are also simultaneously performed in the other two stations 10-2 to 4 stations 10-4.

The ring establishment determination unit 24 of the communication processing unit 17-1 of station 1 10-1 includes all ring establishment confirmation frames 201-1-1 issued by station 1 10-1 from the network in FIG. 6E. When 201-5) is discarded, measurement is started to determine whether or not a ring establishment confirmation frame is completely flowed on the network for more than the frame traversal time obtained in FIG. 6C. That is, the frame traversal time is set in the timer, and it is determined whether or not the ring establishment confirmation frame transmitted by the other communication nodes 10-2 to 10-4 has been detected until the timeout. During this determination, the timer is set again each time the ring establishment confirmation frame transmitted by the other communication nodes 10-2 to 10-4 is received. This is not only to confirm the establishment of the ring of its own country, but also to obtain the fact that other countries have confirmed the establishment of the ring in the East. Then, when the state in which the ring establishment confirmation frame is not observed in the network (ring) continues by the ring establishment determination unit 24 for the frame circulation time T or more from the time of the last observation of the ring establishment confirmation frame, It is determined that all other communication nodes 10-2 to 10-4 on the network can also recognize the configuration (establishment of the ring) of the network connection in the East (FIG. 6F).

In the above description, each station shows a case in which the frame traversal time is calculated using the ring establishment confirmation frame that is returned first among the ring establishment confirmation frames issued by the own station. It is good also as frame circulation time which calculates and sets those average value, the maximum value, etc. in a timer.

According to the second embodiment, when a communication node is connected in a ring shape, the frame traversal time is calculated using the reception time of the ring establishment confirmation frame and the issuing time of the ring establishment confirmation frame, and the ring establishment confirmation frame that last flowed on the network. When the ring establishment confirmation frame did not flow for more than the frame traversal time from the above, all the communication nodes 10 on the network that traversed the frame were judged to be able to recognize the configuration of the ring connection. The frame traversal time can be set according to the number of nodes 10. This sets, for example, the passage time of a frame per communication node in advance, and multiplies this by the number of communication nodes 10 constituting the ring-shaped communication system and the safety factor for excluding the error as the timer setting value. In comparison with the case, the communication node 10 can shorten the time for determining the recognition of the connection configuration of the network.

Embodiment 3.

In the second embodiment, when the communication node that issued the ring establishment confirmation frame receives its own ring establishment confirmation frame, it is discarded (terminated). When the ring establishment confirmation process of the second embodiment is in full swing, if a failure occurs in some of the communication nodes and the communication nodes are separated (dissociated) from the network, a loop back is performed to exclude the communication nodes, thereby forming a new ring. . At this time, there is a possibility that a ring establishment confirmation frame issued by the resolved communication node remains in the new ring. In the third embodiment, a processing method in such a case will be described.

7 is a block diagram schematically showing a functional configuration of a communication node according to the third embodiment. In FIG. 5 of the second embodiment, the communication processing unit 17 of the communication node of the third embodiment has a configuration that further includes a reception frame information management unit 31 and a reception frame information storage unit 32.

Each time the reception frame information management unit 31 repeats the ring establishment confirmation frame issued by the other communication node 10 received from the A port 11, the source communication node for the ring establishment confirmation frame is repeated. Receiving frame information including frame identification information such as a serial number for identifying a frame, and a frame issuing time (or frame receiving time), and is stored in the receiving frame information storage unit 32. Contrast with information. When the received ring establishment confirmation frame is not the same as that received in the past (that is, newly issued), the received frame information storage unit 32 is overwritten with the received frame information of the source communication node ( overwrite) On the other hand, when the received ring establishment confirmation frame is received in the past, the ring establishment confirmation frame is discarded.

The reception frame information storage unit 32 stores reception frame information for each communication node 10 connected to the network. For example, as described in Embodiment 2, when a communication node 10 receives a ring establishment confirmation frame issued every predetermined time, each serial number is different (numbers increase by one). The received frame information of the new ring establishment confirmation frame is overwritten.

The ring establishment confirmation frame issuing unit 21 also has a function of embedding frame identification information such as a serial number for identifying the frame in the ring establishment confirmation frame. When the frame identification information is a serial number, for example, a process of embedding a serial number incremented by one in a ring establishment confirmation frame issued every predetermined time is performed. In addition, the same code | symbol is attached | subjected to the same component as the above-mentioned description, and the description is abbreviate | omitted.

8A to 8D are diagrams schematically showing an example of a processing procedure for discarding a ring establishment acknowledgment frame issued by a communication node dissociated from the network by the occurrence of a failure during the acknowledgment of the connection state of the ring. In the ring establishment confirmation frame issuing unit 21 of the communication processing unit 17-3 of the three stations 10-3, the serial numbers are &quot; No. &quot; 1 "and" No. 2 "first and 2nd ring establishment confirmation frames 202-1 and 202-2 are issued, and those frames are circulating in a ring shape (FIG. 8A).

9A is a diagram showing an example of reception frame information held by four stations in the state of FIG. 8A, and FIG. 9B is a diagram showing an example of reception frame information held by one station in the state of FIG. 8A. An example is shown in which the communication node name that is the transmission source of the ring establishment confirmation frame as the received frame information, the serial number embedded in the ring establishment confirmation frame as the frame identification information, and the time at which the ring establishment confirmation frame is issued are stored. It is also possible to use a MAC (Media Access Control) address unique in the world as the node name. As shown in FIG. 9A, although the station 4 receives the first and second ring establishment confirmation frames 202-1 and 202-2 in order, the fourth station 10-4 receives the second ring establishment confirmation frame 202-2. ) Is the newest, so the reception frame information for the second ring establishment confirmation frame 202-2 is stored. On the other hand, as shown in Fig. 9B, since the first station 10-1 receives only the first ring establishment confirmation frame 202-1, the received frame information is stored. Here, although only four stations 10-4 and one station 10-1 have been described, the other station also acquires and stores received frame information on the ring establishment confirmation frame transmitted from the B port 14 to the East.

Subsequently, it is assumed that a failure occurs in the three stations 10-3. Thereby, the B port 14-2 of the two stations 10-2 and the A port 11-4 of the four stations 10-4 are connected from the three stations 10-3 when the cable is an optical fiber. When light does not come and a cable is an electric wire, it detects that an electric signal does not come from the three stations 10-3, and detects that the fault occurred in the three stations 10-3. As described in Embodiment 1, the station 10-2 loops back at the A port 11-2, and the station 4 10-4 loops back at the B port 14-4. (Fig. 8B). As a result, the ring establishment confirmation frame issued by the three stations 10-3 is left in the new ring established by the loop back. As shown in FIG. 8B, the first ring establishment confirmation frame flows through the atmospheric ring 2.

Subsequently, the first ring establishment confirmation frame 202-1 is received at the B port 14-4 of the station 10-4, and is in the loop back state, thus establishing the first ring from the B port 14-4. The confirmation frame 202-1 is transmitted. Before this transmission, when the reception frame information management unit 31 of the communication processing unit 17-4 of the four stations 10-4 receives the first ring establishment confirmation frame 202-1, the reception frame as described above is received. The information is obtained, and the received frame information is collated with the received frame information of the corresponding three stations 10-3 stored in the received frame information storage unit 32. At this time, the serial number of the first ring establishment confirmation frame 202-1 received is "No. 1 ", but as shown in Fig. 9A, the serial number of the received frame information stored is &quot; No. 2 ", the reception frame information management part 31 recognizes that the received 1st ring establishment confirmation frame 202-1 is a repeating ring establishment confirmation frame in the past, and discards the frame (FIG. 8C).

Orientally, the reception frame information management unit 31 of the communication processing unit 17-4 of the four stations 10-4 also receives the second ring establishment confirmation frame 202-2. 2 ", but as shown in Fig. 9A, the serial number of the received frame information stored is &quot; No. 2 ", the reception frame information management part 31 recognizes the received 2nd ring establishment confirmation frame 202-2 as a repeating ring establishment confirmation frame in the past, and discards the frame (FIG. 8D). By the above, the three stations 10-3 dissociate and the removal process of the ring establishment confirmation frame issued by the three stations 10-3 left in the new ring is performed.

In addition, in FIG. 8C, the first station 10-1, which has received the first and second ring establishment confirmation frames 202-1 and 202-2 flowing through the atmospheric ring 2, does not perform a discard process at first. As described above, a filter is applied to only frames transmitted from the B port 14-1, and data frames flowing from the B port 14-1 to the A port 11-1 are read in the communication node. It is by the assumption that I just send it out without entering it.

In addition, this is an example, and you may make it discard the process of both the data frame sent out from the A port 11 and the data frame sent out from the B port 14. In this case, the reception frame information for the ring establishment confirmation frame transmitted from each port is stored. In the communication node having such a structure, the station 10-1 in FIG. 8C can execute the discarding processing of the first and second ring establishment confirmation frames 202-1 and 202-2. However, if the data frame transmitted from both the A port 11 and the B port 14 is to be discarded or not, processing will take time when the cable transmission speed is high. The processing speed may be slower than the transmission speed of, and the overall communication speed may be lowered.

In addition, in the case of serial numbers in which the frame identification information is incremented one by one as in the above-described example, it is possible to determine the new and old of the ring establishment confirmation frame by using the serial number. Issuance time) is not required. However, in the case where the frame identification information is formed by other symbols or random values, it is necessary to store the received frame information including time (issue time and the like). This is because the addition of time information makes it possible to make a new and old decision on the received ring establishment confirmation frame.

According to the third embodiment, when a ring establishment confirmation process is in full swing, a failure occurs in any one of the communication nodes 10, the communication node 10 dissociates from the network, and after the new ring is formed, it remains in the ring. Since the ring establishment confirmation frame issued by the resolved communication node 10 is discarded, an unnecessary frame of the resolved communication node 10 can be prevented from staying on the ring.

Embodiment 4.

In Embodiment 2, when a ring establishment confirmation frame is finally detected and a ring establishment confirmation frame is not detected during the time more than a frame circulation time, confirmation of the ring connection state is performed. However, during the ring establishment confirmation processing of the second embodiment, if a failure occurs in some communication nodes and the communication nodes are dissociated from the network, a loop back is performed to exclude the communication nodes. In the third embodiment, a method of excluding a ring establishment acknowledgment frame issued by the excluded communication node from the new ring on which the loop is performed has been described. However, in Embodiments 2 and 3 described above, the ring establishment confirmation processing after loop back is not described. Therefore, the fourth embodiment describes a method of performing ring establishment confirmation processing after loop back.

The communication node of the fourth embodiment has the same configuration as that in FIG. 7 of the third embodiment. However, the ring establishment confirmation frame issuing unit 21, in addition to the issue time and the identification number identifying the frame in the ring establishment confirmation frame, the self-communication node 10 at the time of issuance of the ring establishment confirmation frame, the normal A port 11 And the B port 14 further has a function of embedding and transmitting path state information indicating whether it is in a state capable of transmitting and receiving (hereinafter, referred to as a through state) or a loop back state. In the case of the loop back state, information indicating where the A port 11 and the B port 14 is performing the loop back is also included. When the ring establishment acknowledgment frame issuing unit 21 receives the ring establishment acknowledgment frame issued by the own communication node 10, the ring establishment acknowledgment frame issuing unit 21 issues a ring establishment acknowledgment frame when the path state information in the frame is equal to the current path state. If the path state information in the frame is different from the current path state, the issuance of the ring establishment confirmation frame is continued. In that case, the frame circulation time calculation unit does not calculate the frame circulation time. It also has a function to disable it.

10A to 10E are diagrams schematically showing an example of a procedure for confirming a connection state of a new ring formed after a loop back has occurred. 10A to 10E show a state in which the four stations 10-4 focus on the establishment of the ring. First, all of stations 10-1 to 10-4 are in a normal state in which a failure has not occurred, and any communication nodes 10-1 to 10-4 are in a through state. The ring establishment confirmation frame issuing unit 21 of the communication processing unit 17-4 of the four stations 10-4 has a serial number of "No. 1 "and" No. 2 ", and the 1st and 2nd ring establishment confirmation frames 203-1 and 203-2 which embedded the information whose path state information is" Through "and" Through ", respectively, are issued (FIG. 10A).

Subsequently, it is assumed that a failure occurs in the three stations 10-3. Thereby, the B port 14-2 of the 2 stations 10-2 and the A port 11-4 of the 4 stations 10-4 detect that a failure has occurred in the 3 stations 10-3, As described in the first embodiment, the station 10-2 loops back at the A port 11-2, and the station 4 10-4 loops back at the B port 14-4. As a result, the path state of the two stations 10-2 becomes "Loop-A" (not shown) which loops back at the A port 11-2, and the path state of the four stations 10-4 is B. FIG. It becomes "Loop-B" which loops back in port 14-4. When the predetermined time has elapsed since the issuance of the second ring establishment confirmation frame 203-2, the time is T3, the ring establishment confirmation frame issuing unit 21 of the four stations 10-4 has a serial number of "No. 3 "and the 3rd ring establishment confirmation frame 203-3 which embeds the information whose path state information is" Loop-B "is issued (FIG. 10B). If the ring establishment confirmation frame issued by the three stations 10-3 is left in the ring newly configured by the loop back, it is discarded by the above-described third embodiment.

Thereafter, the ring establishment confirmation frame issuing unit 21 of the communication processing unit 17-4 of the four stations 10-4 receives the first ring establishment confirmation frame 203- whose path state information issued by the own station is &quot; through &quot;. 1) is received, but the current station's path state is &quot; Loop-B &quot;, which is the loop back state of the B port 14, and since the two do not coincide, the ring establishment confirmation frame is issued every predetermined time. (FIG. 10C). The received first ring establishment confirmation frame 203-1 is discarded. After that, the second ring establishment confirmation frame 203-2 is also received.

In addition, as time elapses, the ring establishment confirmation frame issuing unit 21 of the communication processing unit 17-4 of the four stations 10-4 establishes a third ring whose route state information issued by the own station is &quot; Loop-B &quot;. When receiving the confirmation frame 203-3, since it matches the "Loop-B" which is the path state of the current station, the issuance of the ring establishment confirmation frame is stopped (Fig. 10D). Using this third ring establishment confirmation frame 203-3, the frame circulation time calculating section 22 calculates the frame circulation time in the order described in the second embodiment. Thereafter, the received third ring establishment confirmation frame 203-3 is discarded.

Thereafter, the four stations (10-4) have a serial number issued by their own station. 4 "and the 4th ring establishment confirmation frame 203-4 whose path state information is" Loop-B ", and a serial number" No. 5 "and the path state information is" Loop-B "after receiving the 5th ring establishment confirmation frame 203-5 in order, and discards each (FIG. 10E). Oriental processing is also performed in other stations. After that, as described with reference to Figs. 6E to 6F of the second embodiment, the ring connection state is confirmed after loop back by confirming that the time elapses from the frame cycle time or more after observing the ring establishment confirmation frame last. The process ends.

According to the fourth embodiment, even when a failure occurs during the process of confirming the connection state of the ring and the communication node 10 decomposed occurs, and the ring configuration is changed, the network node always participates in the network corresponding to the connection state of the new ring. Since at least one of the communicating node 10 can receive the ring establishment confirmation frame 203 issued by the own communication node 10 via the transmission path of the final network, a plurality of additional communication nodes 10 can be received during the ring configuration. Even if the participation of the communication node 10 is withdrawn, the ring configuration can be achieved.

Embodiment 5.

11A to 11C are diagrams showing a state which becomes a problem that may occur during the ring establishment confirmation process. First, it is assumed that stations 1-10-1 to 4-4 are in a state of being connected in a normal state. Then, the ring establishment confirmation frame issuing unit 21 of the communication processing unit 17-3 of the three stations 10-3 is set to "No. 1 "and" No. It is assumed that the first and second ring establishment confirmation frames 204-1 and 204-2, in which the serial number of "2" is embedded, are issued (Fig. 11A).

Subsequently, it is assumed that a failure occurs in the three stations 10-3. Thereby, the B port 14-2 of the 2 stations 10-2 and the A port 11-4 of the 4 stations 10-4 detect that a failure has occurred in the 3 stations 10-3, As described in the first embodiment, the station 10-2 loops back at the A port 11-4, and the station 4 10-4 handles the loop back at the B port 14-4. . As a result, the first and second ring establishment confirmation frames 204-1 and 204-2 issued by the three stations 10-3 are left in the new ring constituted by the loop back (Fig. 11B).

After that, before the first and second ring establishment confirmation frames 204-1 and 204-2 issued by the three stations 10-3 are discarded, five stations instead of the three stations 10-3 that have been dissociated. (10-5) We shall have participated in this network. In this case, the ring is newly configured again, and the two stations 10-2 are moved from the loop back state at the A port 11-2 to the through mode, and the four stations 10-4 are the B ports 14-. In 4), the process moves from the loop back state to the through mode (FIG. 113). As a result, the first and second ring establishment confirmation frames 204-1 and 204-2 issued by the three stations 10-3 in the atmospheric ring 2 travel. These first and second ring establishment acknowledgment frames 204-1 and 204-2 flow in an unused standby ring 2 and, in addition, from port B 14 to port A within each communication node 10. As it flows into the port 11, the filter is not filtered out, so it is not discarded and continues to flow forever.

Therefore, the fifth embodiment describes a method of ring establishment confirmation processing that solves such a problem. 12 is a block diagram schematically showing a functional configuration of a communication node according to the fifth embodiment. The communication processing unit 17 of the communication node of the fifth embodiment has a configuration that further includes a loopback state control unit 51 in FIG. 7 of the third embodiment. In addition, the same code | symbol is attached | subjected to the same component as the above-mentioned description, and the description is abbreviate | omitted.

The loop back state control unit 51 stores the path state transition information indicating the transition of the path state of the self communication node, and the adjacent communication nodes dissociate, and before a new ring is formed, the ring establishment confirmation process ends. If another communication node joins in place of the resolved communication node, the ring establishment confirmation frame issued by the resolved communication node is discarded. Has a function of controlling the port so as not to release the loop back state until (i.e., until the ring establishment confirmation processing ends).

Next, the operation will be described with reference to FIGS. 11A and 13A to 13B. 13A to 13B are diagrams schematically showing an example of a ring establishment confirmation processing procedure when a new communication node joins in place of the resolved communication node. First, as shown in Fig. 11A, stations 1-10-1 to 4-4 are in a connected state in a normal state, and the ring of the communication processing unit 17-3 of three stations 10-3 is connected. The establishment confirmation frame issuing unit 21 displays "No." at the times T1 and T2, respectively. 1 "and" No. Issue a first and second ring establishment confirmation frames embedded with a serial number of 2 &quot;.

Subsequently, it is assumed that a failure occurs in the three stations 10-3. Thereby, the B port 14-2 of the 2 stations 10-2 and the A port 11-4 of the 4 stations 10-4 detect that a failure has occurred in the 3 stations 10-3, As described in the first embodiment, the station 10-2 loops back at the A port 11-2, and the station 4 10-4 loops back at the B port 14-4. At this time, the loop back state control unit 51 of the communication processing units 17-2 and 17-4 of the station 10-2 and station 4 10-4 transitions from the through state to the loop back state. Path state transition information indicating that the operation is performed is stored (FIG. 13A).

In addition, before the first and second ring establishment confirmation frames 205-1 and 205-2 issued by the three stations 10-3 are discarded, five stations ( It is assumed that 10-5) has participated in this network. At this time, the three stations 10-3 detect that the five stations 10-5 have joined the network, but since the three stations 10-5 are in the transitioned state from the through state to the loop back state in the path state transition information, the five stations 10 No ring configuration with -5) is performed (FIG. 13B). That is, to prevent the circulation of the ring establishment confirmation frame issued by the three stations 10-3 in the standby system ring 2 described in FIG. 11C, the loop of the communication processing unit 17-2 of the two stations 10-2 is prevented. The back state control unit 51 keeps the looped-back state at the A port 11-2, and makes the B port 14-2 unusable, and the communication processing unit 17 of the four stations 10-4. The loop back state control unit 51 at -4) keeps looping back at the B port 14-4, and controls the port A 11-4 to be in an unusable state. This state is maintained until the process of confirming a new ring establishment by the loop back in Fig. 13B ends.

Thereafter, as described in the second embodiment, after the ring establishment confirmation frames 205-1 and 205-2 are both discarded on the ring, the two stations 10-2 and the four stations 10-4. The loop back state control unit 51 of the communication processing unit 17 controls the path state from the loop back state to the through state, and also rewrites the path state transition information to the through state. As a result, the ring establishment confirmation frame issuing unit 21 of the two stations 10-2 and the four stations 10-4 performs a new ring establishment confirmation process in the network through the five stations 10-5 that have newly participated. Run In addition, station 2 (10-2) and station 4 (10-4) are communication nodes capable of knowing the end of the ring ring establishment confirmation processing when the station 3 (10-3) dissolves. Since -5) is a communication node which knows that it is a newly joined communication node, new ring establishment confirmation processing is performed from these two stations 10-2 and four stations 10-4.

According to the fifth embodiment, another communication node joins in place of the decommissioned communication node before the adjacent communication node decodes and the ring establishment confirmation frame issued by the communication node 10 exists in the standby system and is discarded. When it is turned on, the ring establishment confirmation frame issued by the resolved communication node on the ring constituted by the participation of a new other communication node can be prevented from continuing to flow without being discarded.

Embodiment 6.

In the sixth embodiment, the configuration of the communication node for preventing the ring establishment confirmation frame from remaining in the atmospheric ring and the processing method thereof will be described. The configuration of the communication node used in the sixth embodiment is the same as that shown in FIG. 7 of the third embodiment. However, the reception frame information management unit 31 of the communication node according to the sixth embodiment traverses the standby system ring 2 and issues the self-communication node among the frames passing from the B port 14 to the A port 11. When receiving frame information including the frame identification information is obtained only for the ring establishment confirmation frame, and in contrast with the received frame information stored in the receiving frame information storage unit 32, the received frame information is not the same as that received in the past. The reception frame information for the ring establishment confirmation frame is stored in the reception frame information storage unit 32, and when the same as that received in the past, the ring establishment confirmation frame is discarded. In addition, the reception frame information storage unit 32 also stores reception frame information of a ring establishment confirmation frame issued by the own communication node among frames that traverse the standby system ring 2 acquired by the reception frame information management unit 31. . In addition, the same code | symbol is attached | subjected to the same component as the above-mentioned description, and the description is abbreviate | omitted.

Next, the operation will be described with reference to Figs. 14A to 14F. 14A to 14F are diagrams schematically showing an example of a discard processing procedure of the ring establishment confirmation frame flowing through the atmospheric system ring. First, the normal ring 1 between the station 10-1 and the station 2-10-2 is disconnected from the state in which stations 1-10-1 to station 4-4 are normally connected. In addition, if the power of one station 10-1 is reduced and turned OFF, the A port 11-2 of the station 10-2 detects that the regular ring 1 is disconnected. As described in the first embodiment, loop back is performed at the B port 14-2. In addition, the B port 14-4 of the four stations 10-4 detects that it is unable to communicate with the one station 10-1, and as described in the first embodiment, the A port 11-4 uses the A port 11-4. Loop back is performed (FIG. 14A).

After that, if the power supply of the station 10-1 is turned on, the B port 14-4 of the station 10-4 detects the return of the station 10-1 and loops. Transition from a back state to a normal through state. In addition, the B port 14-1 of the station 10-1 with the power supplied detects that the normal ring 1 between the station 10-1 and the station 10-2 is disconnected. Then, as described in the first embodiment, loop back is performed at the A port 11-1. The ring establishment confirmation frame issuing unit 21 of the communication processing unit 17-1 of the station 10-1 has a serial number of "No. A ring establishment confirmation frame 220 of 1 "is issued from the A port 11-1 to the atmospheric ring 2 (FIG. 14B).

After that, when the disconnection of the regular ring 1 between the station 10-1 and the station 10-2 is repaired, the B port 14-1 of the station 1 and the station 2 The A port 11-2 detects the repair of the normal ring 1 between each other and transitions from the loop back state to the normal through state (FIG. 14C). As a result, the stations 10-1 to 4-10-4 are connected to the regular ring 1 and can communicate in a state where there is no loop back. Therefore, the ring establishment confirmation frame 220 issued by one station is left in the atmospheric ring 2.

Subsequently, it is assumed that as time elapses, the ring establishment confirmation frame 220 flows through the atmosphere system ring 2 and comes between stations 2-10-2 and stations 1-10-1 (14-4). At this time, the reception frame information management unit 31 of the communication processing units 17-2 to 17-4 of the two stations 10-2 to 4-4 receiving the frame flowing through the atmospheric ring 2 Receive ring establishment confirmation frames 220 issued by B ports 14-2 to 14-4, respectively, but not from A ports 11-2 to 11-4 as they are not issued by the own communication node. It flows to the atmospheric ring 2 and transmits the ring establishment confirmation frame 220.

When the station 10-1 receives the ring establishment confirmation frame 220 issued by the self station from the B port 14-1, the reception frame information management unit 31 of the communication processing unit 17-1 receives the reception frame. The reception frame information of the information storage unit 32 is referred to to determine whether the ring establishment confirmation frame 220 has been received in the past. In this case, since it has not been received in the past, the serial number "No. 1 &quot; is obtained and stored in the reception frame information storage section 32 as reception frame information, and then sent from the A port 11-1 (FIG. 14E).

In addition, the ring establishment confirmation frame 220 then traverses in the atmosphere ring 2, but in station 2 (10-2) to station 4 (10-4), the ring establishment confirmation frame 220 issued by the self station is issued. Because it is not, it transmits as it is. When the ring establishment confirmation frame 220 is received at the B port 14-1 of the station 10-1, the reception frame information management unit 31 of the communication processing unit 17-1 stores the reception frame information storage. Refer to section 32, and the serial number "No. Since the reception frame information corresponding to "1" exists, it is determined that it has been received in the past, and the ring establishment confirmation frame 220 is discarded (FIG. 14F). In addition, although the above description focused on the process of discarding the ring establishment confirmation frame 220 which flows through the atmospheric ring 2 after it became normal state, the normal ring 1 returned to the normal shown in FIG. 14C. In the above, the ring establishment confirmation process described in the above embodiment is performed in parallel.

According to the sixth embodiment, the received frame information is acquired for the ring establishment acknowledgment frame 220 issued by the self-communication node flowing through the atmospheric system ring 2, and the second received ring establishment is performed based on the received frame information. Since the reception frame information management unit 31 of the communication processing unit 17 has a function of discarding the confirmation frame 220, the ring establishment confirmation frame 220 left in the standby ring 2 for some reason is replaced. It has the effect that it can be discarded without remaining in the mechanical ring 2. Since only the ring establishment acknowledgment frame 220 issued by the self-communication node is received and the record transmitted is left, only the ring establishment acknowledgment frame 220 issued by the other node is transmitted. It also has the effect of being able to suppress the load on the processing of the frame flowing through the frame.

Embodiment 7.

In the seventh embodiment, the ring establishment confirmation processing ends, and a failure occurs in a communication node constituting the network in a state where a token frame can transmit a normal communication message flowed into the regular ring 1, and the communication node The ring establishment confirmation process in the case of dissociation from the network will be described.

Fig. 15 is a block diagram schematically showing the functional configuration of a communication node according to the seventh embodiment. The communication processing unit 17 of the communication node of the seventh embodiment has a configuration that further includes the frame discard processing unit 61 in FIG. 12 of the fifth embodiment. In addition, the same code | symbol is attached | subjected to the same component as the above-mentioned description, and the description is abbreviate | omitted.

When the frame discard processing unit 61 is in the ring establishing confirmation processing state, the frame discard processing unit 61 performs a process of discarding frames other than the ring establishing confirmation frame. For example, from the normal transmission state in which a token frame is flowed in a ring, when a failure occurs in some of the communication nodes constituting the network and is dissociated, the state is changed to a ring establishment confirmation processing state, but newly reconstructed at that time. Frames that are not related to ring establishment confirmation processing, such as token frames or data frames, that flow during the established ring are discarded.

16A to 16E are diagrams schematically showing an example of a procedure of deleting a frame irrelevant to the ring establishment confirming process in the case of shifting from the normal communication state to the state of the ring establishing confirming process. First, the network is assumed to be in a normal communication state. Here, it is assumed that the three stations 10-3 have received the token frame 208 from the two stations 10-2 and obtained the transmission right. Thereafter, the third station 10-3 receives a token indicating that the own station (the station 10-3) has obtained the token frame 208 for the station 10-2 that is the source of the token frame 208. The token frame 208 is released after transmitting the completion notification frame 206 and transmitting the data frame 207 to the communication node of the counterpart to whom the data is to be sent (FIG. 16A).

Thereafter, a failure has occurred in three stations 10-3 (Fig. 16B). Thereby, the B port 14-2 of the 2 stations 10-2 and the A port 11-4 of the 4 stations 10-4 detect that a failure has occurred in the 3 stations 10-3, As described in the first embodiment, the station 10-2 loops back at the A port 11-2, and the station 4 10-4 loops back at the B port 14-4. As a result, the token reception completion notification frame 206 and the data frame 207 issued by the three stations 10-3 are left in the new ring formed by the loop back. In addition, the two stations 10-2 and the four stations 10-4, which have detected that a failure has occurred in the three stations 10-3, transition from the normal communication state to the ring establishment confirmation processing state. Therefore, the ring establishment confirmation frame issuing units 21 of the communication processing units 17-2 and 17-4 of the station 2 10-2 and station 4 10-4 each have a ring establishment confirmation frame 209-. 1, 210-1) are started (FIG. 16C). At this time, the station 10-1 is still in a normal communication state. Therefore, upon receipt of the token reception completion notification frame 206 from the A port 11-1, the token reception completion notification frame 206 is sent to the B port 14-1 as it is not in front of the own station.

In addition, since the station 10-2 is in a state of issuing the ring establishment confirmation frame 209-2 at predetermined time intervals, the station 10-2 waits for a return of the ring establishment confirmation frame sent by the station. have. At this time, if the frame discard processing unit 61 of the communication processing unit 17-2 detects a frame that is not related to the ring establishment confirmation processing state among the frames received from the A port 11-2, it discards (Fig. 16D). ). Here, the received token reception completion notification frame 206 is discarded. The four stations 10-4 also issue the ring establishment confirmation frame 210-2 at predetermined time intervals.

At this time, the first station 10-1 receives the first ring establishment confirmation frame 210-1 from the fourth station 10-4 from the A port 11-1, and the B port 14-1. The processing to send out is performed. As a result, the ring establishment acknowledgment frame issuing unit 21 of the communication processing unit 17-1 of the station 10-1 knows that it has transitioned to the ring establishment acknowledgment state, and starts issuing a ring establishment acknowledgment frame of the local station. . Further, the data frame 207 issued by the three stations 10-3 is received before the ring establishment confirmation frame 210-1 from the four stations 10-4, and the data frame 207 is received. At this time, the station 10-1 does not discard the data frame because it is not in the ring establishment state.

Thereafter, the frame discard processing unit 61 of the communication processing unit 17-2 of the station 10-2 receives the data frame issued by the station 10-3 received from the port A-11-2. 207), a process for discarding (Fig. 16E) is performed. As described above, after the transition from the normal communication state to the ring establishment confirmation processing state, the process of discarding the issued frame in the normal communication state left in the new ring is completed. Thereafter, the ring establishment confirmation processing is performed in the order described in the second to fifth embodiments.

According to the seventh embodiment, when the transition from the normal communication state to the ring establishment confirmation processing state occurs, the situation in which the issued frame stays in the new ring in the communication state can be avoided.

Embodiment 8.

In the eighth embodiment, after the ring establishment is performed in the above-described second to sixth embodiments, a station information notification process for spreading station information about each communication node to all communication nodes on the network will be described.

17 is a diagram schematically showing a functional configuration of a communication node according to the eighth embodiment. The communication processing unit 17 of this communication node includes a ring establishment confirmation processing unit 20, a station information management unit 71, a frame traversal time calculation unit 72, a frame traversal time storage unit 73, and a station information notification completion determination unit ( 74 and a network configuration information storage unit 75. In addition, the ring establishment confirmation processing part 20 bundles each processing part in the communication processing part 17 which performs the ring establishment confirmation process demonstrated in each Embodiment 2-6. In addition, the same code | symbol is attached | subjected to the same component as the figure used in embodiment mentioned above, and the description is abbreviate | omitted.

After the ring establishment is made in the above-described Embodiments 2 to 6, the station information management unit 71 supplies the station information of the self-communication node necessary for creating the configuration information of the network to all communication nodes in the network where the ring is established. The included station information notification frame is issued every predetermined time. In this station information notification frame, the time at which the station information notification frame was issued is embedded. In addition, the station information management unit 71 stops issuing the station information notification frame after the point in time of first receiving the station information notification frame transmitted by the station information management frame and discards the received station information notification frame. Here, the station information is a loop back state indicating which port is in the loop back state when the self communication node identification information such as the MAC address of the self communication node, the station number identifying the self communication node, and the self communication node are in the loop back state. Information, and MAC addresses of communication nodes located upstream and downstream. When the station information management unit 71 receives the station information notification frame sent by another communication node, the station information management unit 71 stores the station information in the network configuration information storage unit 75.

The frame traversal time calculation unit 72 determines the time when the station information notification frame was received by the self-communication node from the A port 11 and when the station information notification frame was received and the issue time embedded in the station information notification frame. The difference is calculated, and the frame traversal time, which is the time at which the station information notification frame traverses the ring, is obtained. The frame circulation time storage section 73 also stores the frame circulation time calculated by the frame circulation time calculation section 72.

After the station information notification completion determination unit 74 stops issuing the station information notification frame, and finally receives the station information notification frame issued by the self-communication node or another communication node, the station information notification completion determination unit 74 has a time greater than or equal to the frame traversal time, It is determined whether or not the state in which the station information notification frame is not detected continues. If the state continues for more than the frame traversal time, it is determined that all communication nodes on the network have acquired station information from each other.

The network configuration information storage unit 75 stores network configuration information which is station information associated with a communication node constituting a network in which a ring is established. In other words, the network configuration information is information managed by matching station information received from another communication node to the communication node. By this network configuration information, each communication node can know the connection state of the network in which the ring was established, and the like.

18A to 18F are diagrams schematically showing an example of a station information notification processing procedure in a ring-shaped communication system. First, the station information management unit 71 of the communication processing unit 17-1 of the station 10-1 receives the station information notification frame including the station information of the station 10-1 that has purchased the issuing time. 14-1) to the normal ring 1 (FIG. 18A). Here, the station 10-1 transmits the first station information notification frame 211-1 including the station information 1-info of the station 10-1 at time T1, and predetermined from time T1. It is assumed that the second station information notification frame 211-2 including the station information 1-info of the station 10-1 is sent to the regular ring 1 at the time T2 after which time has elapsed.

After that, since the station 10-1 has not received the station information notification frame sent by itself, the station 10-1 does not receive the third and fourth station information notification frames 211-3 and 211-4 at the times T3 and T4, respectively. In addition, it transmits to the regular ring 1. Thereafter, the first station information notification frame 211-1 first issued by station 10-1 is lost between the station 4 and the station 10-1 for some reason. (Fig. 18b). When the communication nodes 10-2 to 10-4 other than the station 10-1 receive the station information notification frame from the station 10-1, the communication processing units 17-2 to 17-. The station information management unit 71 of 4) copies the station information, and stores the station information in association with the station 10-1 in the network configuration information storage units 75-2 to 75-4.

Subsequently, the station 10-1 receives the second station information notification frame 211-2 issued by the station 10-1. In one station 10-1, since the first station information notification frame 211-1 is lost on the network, the second station information notification frame 211-2 becomes the first station information notification frame received. The reception time T6 is stored. The frame traversal time calculation unit 72 of the communication processing unit 17-1 of the station 10-1 issuing time T2 embedded in the frame from the reception time T6 of the second station information notification frame 211-2. The frame traversal time T (= T6-T2) obtained by subtracting is calculated (FIG. 18C). The calculated frame circulation time is stored in the frame circulation time storage unit 73. In addition, the station information management unit 71 of the communication processing unit 17-1 of the station 10-1 discards the returned second station information notification frame 211-2 from the network. In addition, since the station information management unit 71 of the communication processing unit 17-1 of the station 10-1 first received the station information notification frame issued by itself, the issuance of the station information notification frame is stopped thereafter. (FIG. 18D). Further, up to this point, the station 10-1 has issued up to the fifth station information notification frame 211-5.

Thereafter, the station 10-1 performs a process of receiving and discarding the station information notification frame issued by the own station in order, and receiving the fifth station information notification frame 211-5 issued last, By discarding, the station information notification frame issued by the station 10-1 from the network disappears (Fig. 18E). 18A to 18E are simultaneously performed in the other two stations 10-2 to 4 stations 10-4 constituting the network.

The station information notification completion determination unit 74 of the communication processing unit 17-1 of the station 10-1 receives all station information notification frames 211- issued by the station 10-1 from the network in Fig. 18E. When 1 to 211-5) are discarded, measurement is started for whether or not the station information notification frame flows on the network at least for the frame traversal time obtained in Fig. 18C. That is, the frame traversal time is set in the timer, and it is determined whether or not the station information notification frame sent by the other communication nodes 10-2 to 10-4 is detected until the timeout is reached. During this determination, when the station information notification frame transmitted by the other communication nodes 10-2 to 10-4 is received from the A port 11-1, the timer is set again each time. This not only confirms that the station information of the own station is spread over all communication nodes (10-1 to 10-4), but also confirms that the station information of other stations is spread over all communication nodes (10-1 to 10-4) in the East. For that. Then, the station information notification completion determination unit 74, if the state where the station information notification frame is not observed in the network continues after the issuance of the station information notification frame or more than the frame traversal time T, that is, the timer is timed out. When it is out, it is determined that all other communication nodes on the network can spread station information to all communication nodes in the East (FIG. 18F). Also, " 2-info ", " 3-info " and " 4-info " in FIG. 18F indicate station information included in the station information notification frame transmitted by each of the 2 stations, 3 stations, and 4 stations.

According to the eighth embodiment, since the station information notification frame including the station information of the self-communication node is circulated after the ring establishment, the station information notification frame is returned to the own station, so that other stations notify the station information. You can see that the frame is received. This eliminates the need for receiving a response message from each communication node after notifying the station information to each communication node as in the case of the conventional Ethernet or the like, so that the required number of frames can be reduced. This has the effect of easily confirming that the station information of all communication nodes is shared.

In addition, since the communication node continues to issue the station information notification frame and stops issuing the station information notification frame when the station information notification frame issued by the communication node returns to the beginning, the communication node disappears on the path of the station information notification frame. In addition, it is possible to prevent the congestion of the notification of the station information and to shorten the corresponding time when the station information notification frame is lost.

In addition, since the frame traversal time for which the station information notification frame traverses was measured and the frame traversal time was used to determine whether all communication nodes on the network spread station information across each other, the ring configuration (number of communication nodes) In accordance with this, it is possible to set a time (timeout value) for determining whether all communication nodes have spread the station information over each other. As a result, the timeout value is different in a ring configuration with a small number of communication nodes and a ring configuration with a large number of communication nodes. Therefore, when the number of communication nodes is small, the setting of station information exchange is completed more quickly.

As described above, the Ethernet-based ring-shaped communication system according to the present invention is useful for a network composed of a plurality of communication nodes.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows schematic structure of the ring-shaped communication system of Ethernet base which concerns on this invention.

FIG. 2 is a block diagram schematically showing a configuration of a communication node constituting the ring-shaped communication system of FIG. 1.

3 is a diagram schematically showing a state in which a failure occurs in a ring-shaped communication system.

4 is a diagram schematically showing a state in which a cable is incorrectly connected at the time of ring configuration of a ring-shaped communication system.

5 is a block diagram schematically showing a functional configuration of a communication node according to the second embodiment.

It is a figure which shows typically an example of the ring establishment confirmation process sequence in ring-shaped communication system (1 of them).

FIG. 6B is a diagram schematically showing an example of a ring establishment confirmation processing procedure in the ring-shaped communication system (of which 2).

FIG. 6C is a diagram schematically showing an example of a ring establishment confirmation processing procedure in a ring-shaped communication system (of which 3).

6D is a diagram schematically showing an example of a ring establishment confirmation processing procedure in the ring-shaped communication system (of which 4).

FIG. 6E is a diagram schematically showing an example of a ring establishment confirmation processing procedure in the ring-shaped communication system (of which 5).

6F is a diagram schematically showing an example of a ring establishment confirmation processing procedure in the ring-shaped communication system (of which 6).

7 is a block diagram schematically showing a functional configuration of a communication node according to the third embodiment.

8A is a diagram schematically showing an example of a processing procedure for discarding the ring establishment confirmation frame (one of which).

8B is a diagram schematically showing an example of a processing procedure for discarding the ring establishment confirmation frame (of which 2).

FIG. 8C is a diagram schematically showing an example of a processing procedure for discarding the ring establishment confirmation frame (of which 3).

FIG. 8D is a diagram schematically showing an example of a processing procedure for discarding the ring establishment confirmation frame (of which 4).

FIG. 9A is a diagram showing an example of received frame information held by four stations in the state shown in FIG. 8A.

FIG. 9B is a diagram showing an example of received frame information held by one station in the state shown in FIG. 8A.

10A is a diagram schematically showing an example of a procedure for confirming a connection state of a new ring formed after a loopback has occurred (1 of them).

FIG. 10B is a diagram schematically showing an example of a procedure for confirming a connection state of a new ring formed after a loopback occurs (two of them).

FIG. 10C is a diagram schematically showing an example of a procedure for confirming a connection state of a new ring formed after a loop back has occurred (3 of them).

FIG. 10D is a diagram schematically showing an example of a procedure for confirming a connection state of a new ring formed after a loop back has occurred (4 of them).

FIG. 10E is a diagram schematically showing an example of a procedure for confirming a connection state of a new ring formed after a loopback has occurred (of which 5).

Fig. 11A is a diagram showing a state that becomes a problem that may occur during the ring establishment confirmation process (one of them).

Fig. 11B is a diagram showing a state that becomes a problem that may occur during the ring establishment confirmation process (of which 2).

Fig. 11C is a diagram showing a state that becomes a problem that may occur during the ring establishment confirmation process (of which 3).

12 is a block diagram schematically showing a functional configuration of a communication node according to the fifth embodiment.

FIG. 13A is a diagram schematically showing an example of a ring establishment confirmation processing procedure when a new communication node participates in place of the resolved communication node (1 of them).

FIG. 13B is a diagram schematically showing an example of a ring establishment confirmation processing procedure when a new communication node joins in place of the resolved communication node (of which 2).

It is a figure which shows typically an example of the disposal process sequence of the ring establishment confirmation frame which flows through an atmospheric system ring (1 of them).

It is a figure which shows typically an example of the disposal process procedure of the ring establishment confirmation frame which flows through an atmospheric system ring (of which 2).

FIG. 14C is a diagram schematically showing an example of the discard processing procedure of the ring establishment confirmation frame flowing through the atmospheric system ring (3 of which).

FIG. 14D is a diagram schematically showing an example of a discard processing procedure of the ring establishment confirmation frame flowing through the atmospheric system ring (of which 4).

FIG. 14E is a diagram schematically showing an example of a discard processing procedure of the ring establishment confirmation frame flowing through the atmospheric system ring (of which 5).

14F is a diagram schematically showing an example of a discard processing procedure of the ring establishment confirmation frame flowing through the atmospheric system ring (6 of them).

Fig. 15 is a block diagram schematically showing the functional configuration of a communication node according to the seventh embodiment.

16A is a diagram schematically showing an example of a procedure of deleting a frame irrelevant to the ring establishment confirmation process (one of which).

FIG. 16B is a diagram schematically showing an example of a procedure of deleting a frame irrelevant to the ring establishment confirmation process (of which 2).

FIG. 16C is a diagram schematically showing an example of a procedure for deleting a frame irrelevant to the ring establishment confirmation process (of which 3).

FIG. 16D is a diagram schematically showing an example of a procedure for deleting a frame irrelevant to the ring establishment confirmation process (of which 4).

FIG. 16E is a diagram schematically showing an example of a procedure of deleting a frame irrelevant to the ring establishment confirmation process (of which 5).

17 is a diagram schematically showing a functional configuration of a communication node according to the eighth embodiment.

18A is a diagram schematically showing an example of a station information notification processing procedure in a ring-shaped communication system (one of them).

18B is a diagram schematically showing an example of a station information notification processing procedure in a ring communication system (of which 2).

18C is a diagram schematically showing an example of a station information notification processing procedure in a ring-shaped communication system (of which 3).

18D is a diagram schematically showing an example of a station information notification processing procedure in a ring-shaped communication system (of which 4).

18E is a diagram schematically showing an example of a station information notification processing procedure in a ring communication system (of which 5).

18F is a diagram schematically showing an example of the station information notification processing procedure in the ring-shaped communication system (6 of them).

Explanation of the sign

1 regular ring

2 atmospheric ring

10, 10-1 to 10-5 communication nodes

11, 11-1 to 11-5 A ports

14, 14-1 to 14-5 B ports

17, 17-1 ~ 17-5 Communication Processing Unit

20 ring establishment confirmation processing unit

21 Ring establishment confirmation frame issue

22, 72 frames traversal time calculator

23, 73 frame traversal time memory

24 ring establishment judgment part

31 Receive frame information management unit

32 frame information storage

51 Loopback Status Control

61 Frame Disposal Unit

71 Bureau of Information Management

74 National Information Notification Completion Decision Department

75 Storage of network configuration information

Claims (17)

A communication node constituting a communication system in which a plurality of communication nodes connected by Ethernet are connected in a ring shape, First and second ports having an input unit for inputting a frame and an output unit for outputting the frame; When the communication is normal, when the frame input processing is performed from the input unit of the first port, the frame is transmitted from the output unit of the second port, and when a communication error occurs between adjacent communication nodes, Loop back processing of receiving a frame input from an input of a port connected to an adjacent communication node and a port on the other side, and transmitting the frame from an output of the same port as the input of which the frame is input. When a communication error occurs at a portion different from that of an adjacent communication node, and each communication node sandwiching the communication error portion performs loop back processing, the frame inputted from the input portion of the second port is used. Communication processing means for transmitting the frame from an output of the first port without performing reception processing; Ratio, The communication processing means, At the time of power-up or when loopback processing is performed by itself to form a new ring, a ring establishment acknowledgment frame which embeds an issuing time is generated, and when the ring establishment acknowledgment frame that has traversed the ring is received, thereafter, Ring establishment confirmation frame issuing means for stopping issuance of a ring establishment confirmation frame of Frame traversal time calculation means for calculating a frame traversal time issued by the ring establishment confirmation frame issuing means and subtracting the issuance time in the ring establishment confirmation frame from the time when the ring establishment confirmation frame that has traveled the ring is received. and, And ring establishment determination means for determining whether a ring establishment confirmation frame flowing through the ring is not detected for a period greater than or equal to the frame traversal time after issuance of the ring establishment confirmation frame. The method according to claim 1, The ring establishment confirmation frame issuing means of the communication processing means has a function of embedding in the ring establishment confirmation frame unique information for uniquely identifying the frame, The communication processing means Reception frame information storage means for storing a transmission source communication node of a ring establishment confirmation frame received from another communication node in the communication system, and reception frame information including the unique information; The received ring establishment confirmation frame is received in the past by comparing the received frame information acquired from the ring establishment confirmation frame from the other communication node with the reception frame information corresponding to the other communication node in the reception frame information storage means. And a frame, further comprising receiving frame information management means for discarding the frame. The method according to claim 1, The communication processing means, After an adjacent communication node disconnects from the ring and performs a loop back process to form a new ring, the communication node different from the position of the adjacent communication node before the ring establishment confirmation process in this ring ends. And loop back state control means for controlling the loop back state to hold the loop back state until the ring establishment confirmation process in the ring ends, when. The method according to claim 2, When a communication node of the plurality of communication nodes has made a normal transition from the loop back process, the reception frame information management means automatically issues a ring among self-established ring establishment confirmation frames inputted from an input of a second port. Obtains reception frame information including unique information of the establishment confirmation frame; If the received frame information storage means does not have the same received frame information, the obtained received frame information is stored in the received frame information storage means, And a function of discarding the ring establishment confirmation frame when there is the same received frame information. The method according to claim 1, The communication processing means And a frame discard processing means for discarding frames other than the ring establishment confirmation frame among the received frames when a token frame is flowed in the ring and communicated by the token passing method to the ring establishment confirmation state. And a communication node. The method according to claim 1, And said ring establishment confirmation frame issuing means of said communication processing means transitions to a ring establishment confirmation processing state when it detects reception of a ring establishment confirmation frame, and starts issuing a ring establishment confirmation frame. The method according to claim 1, The communication processing means Upon completion of the ring establishment confirmation process, a station issuing a station information notification frame containing station information about a self-communication node necessary for creating network configuration information, and a station receiving the station information notification frame that has traversed the ring. A communication node comprising information management means. The method of claim 7, And said station information management means of said communication processing means issues a station information notification frame until said issued station information notification frame traverses said ring. The method according to claim 8, The station information management means of the communication processing means embeds the issuing time of the frame into the station information notification frame and, upon receiving the station information notification frame that has traversed the ring, issuing a station information notification frame thereafter. Has the additional ability to stop, The communication processing means Frame traversal time calculation means for calculating a frame traversal time which is issued by the station information management means and subtracts the issuance time in the station information notification frame from the time when the station information notification frame that has traveled the ring is received; Further comprising station information notification completion determining means for determining whether or not to detect the station information notification frame flowing in the ring for more than the frame traversal time after issuing the station information notification frame. . A ring establishment confirmation method for a communication system in which a plurality of communication nodes connected by Ethernet are connected in a ring shape, The communication node acquires and issues a ring establishment confirmation frame by purchasing the issuing time of the frame when the power is turned on or when the self-communication node which is one of the plurality of communication nodes performs a loop back process to form a new ring. A ring establishment acknowledgment frame issuing process of stopping the issuance of subsequent ring establishment acknowledgment frames upon receiving the ring establishment acknowledgment frame; A ring establishment confirmation step of confirming that a ring is established by the communication node receiving a ring establishment confirmation frame issued in the ring establishment confirmation frame issuing step, The ring establishment confirmation process A frame traversal time calculating step of calculating a frame traversal time obtained by subtracting an issuance time in the ring establishment confirmation frame from the time when the ring establishment confirmation frame is received; And a ring establishment determination step of confirming that the ring is established when the ring establishment confirmation frame does not flow over the ring after stopping the issuance of the ring establishment confirmation frame. Ring establishment confirmation method of communication system to perform. The method according to claim 10, In the ring establishment confirmation frame issuing process, unique information for uniquely identifying the frame is embedded in the ring establishment confirmation frame, A reception frame information storage step of storing a transmission source communication node of a ring establishment confirmation frame received from another communication node in the communication system and reception frame information including the unique information; When the received frame is a frame received in the past, the received frame information obtained from the ring establishment confirmation frame received from the other communication node is compared with the received frame information corresponding to the other communication node already stored. And a receiving frame information management step of discarding the frame. The method according to claim 10, After the first communication node dissociates from the ring, performs a loop back process, and a new ring is formed, before the ring establishment confirmation process ends on the new ring, the second communication node is located at the position of the first communication node. If you have participated, A communication node adjacent to the second communication node further includes a loop back control step of maintaining the state of the loop back process until the ring establishment confirmation process on the new ring ends. How to check ring establishment of communication system. The method of claim 11, In a case where any one of the plurality of communication nodes transitions normally from a state in which loopback processing is performed, in the reception frame information management step, a ring establishment confirmation is input in which the autonomous node is input from an input of a second port. Receiving frame information including unique information of a ring establishment confirmation frame issued by the self-communication node among frames, If there is no received frame information stored for the acquired frame, the acquired received frame information is stored, And a process for discarding the ring establishment confirmation frame when there is received frame information for the acquired frame. The method according to claim 10, In the case where a token frame is flowed in the ring and communication is performed by the token passing method, the process proceeds to the ring establishment confirmation step of confirming ring establishment. And a frame discard processing step of discarding frames other than the ring establishment confirmation frame among the received frames. The method according to claim 10, And further comprising a station information management step of transmitting a station information notification frame including station information about the self-communication node necessary for creating network configuration information after the ring establishment confirmation step. checking way. 16. The method of claim 15, And in the station information management step, issue a station information notification frame until the issued station information notification frame traverses the ring and returns. 18. The method of claim 16, In the station information management step, when the issuing time of the frame is embedded in the station information notification frame, and when the issued station information notification frame is received, the subsequent issuance of the station information notification frame is stopped. A frame traversal time calculating step of calculating a frame traversal time obtained by subtracting the issuance time in the station information notification frame from the time at which the station information notification frame issued in the station information management step that has traveled the ring is received; After stopping the issuance of the station information notification frame, when the station information notification frame does not flow for more than the frame traversal time, the station information notification is determined to have been exchanged between communication nodes on the network. And a determination step, further comprising a ring establishment confirmation method for the communication system.

Images